What restrictions are there on carry-on-luggage?

The restrictions on carry-on luggage are specified by the airlines and are determined mainly by weight and size. Check with your airline for the details and be sure to follow them as there are logistical issues to be considered. There are other restrictions with regard to the carriage of liquids, aerosols and gels. These are a security matter which all airports are bound to uphold and so they are strictly enforced. Observe the 3-1-1 rule spelled out in the security and regulations page.